This invention relates generally to appliances having resistive heating elements and thermal protective apparatus used with such appliances and more particularly to thermal protectors having thermostatic discs movable from a circuit engaging position to a circuit disengaging position upon reaching a preselected elevated temperature to thereby de-energize an appliance having an electrically energizable heating element.
Appliances such as coffee makers, steam cookers, steam irons and the like, typically have a sheathed heating element having a relatively rigid terminal pin at each end. Line current is connected through an on/off switch to a thermostat, thermally coupled to the heating element, and in turn to the heating element so that energization of the heating element is cycled on and off to maintain the temperature of the heating element within selected upper and lower limits.
Safety concerns require that a back-up mechanism be provided to de-energize the heating element in the event that the thermostat malfunctions in order to prevent run-away conditions with concomitant excessive temperatures and the possibility of starting a fire. Conventionally, in a coffee maker, for example, a fuse is serially connected to each side of the power source lines, i.e., both to the "hot" and neutral sides. Each fuse is inserted into an electrically insulative sleeve and held in close thermal contact with the sheathed heating element by means of a clip. While this can be effective as a safety back-up mechanism, it requires the addition of several components and assembly operations.